Emergency device for hydraulic control systems



Jufiy 113, 1943., u MERCER 7 2,323,292?

EMERGENCY DEVICE FOR HYDRAULIC CONTROL SYSTEMS Filed May 15, 1940 ?atented July 13, 1943 4 Claims.

The present invention relates to emergency devices for-hydraulic control systems including an emergency conduit connected to a source of fluid under pressure, preferably independent of the source of fluid under pressure from which the normal conduit is fed.

These systems including an emergency conduit may be employed in particular in connection with aircrafts, for the control of retractable landing gears, flaps, and so on. They are applicable, a a rule, whenever it is desired to obtain a perfect safety of operation.

In systems of this kind, the emergency c'onduit feeds the fluid under pressure to the pressure fluid servo-motor which actuates the parts to be moved, from a separate source of pressure, when the normal source of pressure or th circuit connecting this source to the operating servo-motor fails to work. Preferably, in these systems, the normal conduit and the emergency conduit are connected to the same check valve or distributor located in the immediate vicinity of the servomotor to be controlled. This distributor, this valve, this check valve, or the like, is, for this purpose, preferably subjected to the' action of a constant elastic return force which tends to close the-emergency conduit as long as the pressure supplied through the normal feed conduit remains above a predetermined value. trary, thi valve or distributor automatically opens the emergency conduit, while simultaneously closing the normal feed conduit whenever the pressure existing in the normal feed conduit drops to an insufficient value, that is to say below the above mentioned predetermined value.

Hydraulic control systems of thi kind give, as a. rule, perfectly satisfactory results in most cases. But it has been found that, sometimes, the ervomotor is not operated, despite the provision of the emergency conduit connected to a separate source of fluid under pressure. This may happen if, for instance, the outflow of the fluid from the servomotor is impeded or stopped for some reason, for

instance as a consequence of jamming or flattening of the exhaust conduit at any place whatever.

In this case, a high counter-pressure is exerted On the con v 2,323,927 UNITED STATES PATENT, OFFICE- EMERGENCY DEVICE FOR HYDRAULIC CONTROL SYSTEMS Jean Mercier, Neuilly-sur-Seine, France; vested in the Alien Property Custodian Application May 15, 1940, Serial No. 335,383

' In France June 2, 1939 to work. Consequently, the fluid fed by the emergency conduit, instead of operating the servo-motor in the desired direction, passes through the injured circuit and escapes at the place where it is broken or injured. It may also 1 happen that this counterpressure produced by a jamming or breaking of the exhaust circuit is sufiiciently high for preventing the operation of the servo-motor by the fluid fed through the emergency conduit, without preventing the normal working of the distributor or other valve which cuts oil? the normal circuit while opening the auxiliary circuit.

'Ifhe object of the present invention is to provide a system of the type above described which is better adapted to meet the requirements of practice than those of the same kind used for the same purpose up to the present time, and in particular a. system which obviates the drawbacks just above mentioned.

For this purpose, according to an essential feature of the present invention, I provide, on each servo-motor to which lead the normal and auxiliary feed conduits as above referred to, a distributing device of any type whatever, such as a slide valve device, a check valve device, etc., arranged in such manner that, in the case of the normal feed circuit failing to work, said distributing device not only cuts off this feed circuit and places the servo-motor in communication with the emergency circuit, but also, in the course of the same operation, simultaneously connects one side of the servo-motor with the atmosphere. This has for its effect to eliminate all the counter-pressures which might oppose the working of the servo-motor under th action of the fluid under pressure fed from the emergency circuit.

Other features of the present invention will result from the following detailed description of Fig. 2 is a view, similar to Fig. 1, showing the positionof the distributing device when the jack of Fig. 1 is fed with fluid under pressure from the emergency source;

Fig. 3 shows, in an analogous manner, still another embodiment of the invention, as applied to v a single acting servo-motor.

In the embodiment of Fig. 1, a servo-motor 20 includes a cylinder in which is movably mounted a piston 2|. In the immediate vicinity of this servo-motor, I provide a distributing device 22 which, in the example illustrated by th drawing, is of the slide-valve type. The movable element, which is frictionally engaged in 22, of thi device is designated by reference character 23. Of course, I might also make use of a distributor of another suitable type, such as a check valve distributor or a rotary valve distributor, or the like.

Reference characters 24 and 25designate two conduits of the normal feed circuit, which Open, respectively, at 26 and 21 into body 22. This distributor body is connected. on the other hand, at

a check valve which prevents the outflow of the 1 fluid back from body 22 into conduit 32, while permitting the incoming fluid to enter said body 22. This conduit 32 acts as emergency conduit intended to act when the normal feed conduit fails to work.

The system above described will work in the following manner:

In the position of the parts illustrated by Fig. 1, slide valve 23 places conduit 24 in communication with the chamber of servo-motor 20, and conduit 25 in communication with chamber 36 of the same servo-motor.

Thus, if conduit 24 is fed with the fluid under pressure from the normal source, and if conduit 25 is connected to the exhaust, piston 2i is moved in the direction of arrow f. If. on the contrary, it is conduit 25 which is fed with fluid under pressure from the source while conduit 24 is connected to the exhaust. piston 2| is displaced in the direction of arrow f.

The distributing device which controls these two conduits 24 and 25 is not shown and it may be made of any suitable structure, either conventional or not. I have found useful a distributing deviceasshown in Figure 1. including four poppet valves and means to control these valves from the outside. The operation of this device is as follows: Pipe 40 is connected to a source of fluid under pressure and pipe 4| to a return reservoir or to the atmosphere. The fluid arriving through pipe 40 enters chamber 42 which communicates through passage 43 with the corresponding chamber 44. Chambers 42 and 44 are separated by poppet valves 45 and 46 from chambers 41 and 43.- Chamber 41. is connected by conduit 25 to port 21 in body 22. Chamber 48 is connected by conduit 24 to port 28 in the same body. Two further poppet valves, 49 and 50, separate chambers 41 and 48 from chamber 5i in the bottom part of the control device. Shaft 52 disposed in chamber 5| carried double cams 53 and 53' and single cams 54 and 54'. These cams are adapted to engagethe spindles of the poppet valves. valves 45 and 46 pass through the center of the lower poppet valves 49 and 50. The single earns 54 and 54' are adapted to engage the spindles of the upper poppet valves and to lift them and the double cams 53 and 53' are adapted to act accordingly on the'spindles of the lower poppet valves. Shaft 52 projects at one end to the outside and and its position can be controlled manually by lever 55 attached to the projecting end.

In the position shown in the drawing, fluid under pressure will be admitted through pipe 40 into chamber 42 and through passage 43 into chamber 44. Poppet valve 48 being lifted by the action of single cam 54 on its spindle, fluid will flow from chamber 44 through chamber 48 and conduit 24 to port 23 and from there through the body and conduit 28 to one end of jack 20. This will move the piston in the direction of arrow h. The fluid discharged from chamber The spindles of upper poppet 36 is exhausted through conduit 28-and port 21. From there it will flow through conduit 25 into chamber 41 and through poppet valve 49 which is lifted due to the action of double cam 53' on its spindle, into chamber 5| and thence to the return reservoir.

If the position of lever 55 is reversed, cam 54' will cease. to act on poppet valve 48, which will accordingly be closed. On the other hand, double cam53 will then be engaging the spindle of poppet valve 50, which will accordingly be opened. The action on poppet valves 45 and 49 will be the reverse. so that 45 will be open and 49 shut. In this position, fluid under pressure will be admitted through chamber 42, conduit 25, port 21 and conduit 29, and the discharge will take place through conduit 28, port 28, conduit 24, chamber 48. p ppet valve 50 and chamber 6 I.

When some breakdown occurs in the feed circuit, the pilot opens cock 33. which has for its effect to admit into the distributor the pressure existing in the auxiliary, or emergency, circuit. It will be seen, from the drawing, that this pressure acts on the left hand side of slide valve 23."

in such manner as to put this slide valve toward the right while releasing, or opening the orifice of conduit 3|, and closing the openings 28 and 21 of conduits 24 and 25 (see Fig. 2). It is clear that, in this position, the whole distributing device, and consequently the servo-motor, is sepa- The pressure supplied by the emergency circuit acts, through distributor body 22, on piston 2i. so as to move the latter in the direction of arrow This action cannot be disturbed by a counter-pressure existing. in chamber 36, since this chamber is directly connected to the atmosphere through conduit 3|. The displacement of piston 2| in the direction of arrow 1 as produced by the pressure supplied in the emergency circuit by the auxiliary source, corresponds to the operations the correct working of which is absolutely necessary, such for instance as the expansion of the retractable landing gear in order to permit landing.

Distributing device 22 is shown in the drawing without means to restore the'movable element Gil , desired to use the distributing device again withv 23 to the position in which it is shown if the said element should be displaced into another dismounted and afterwards reassembled, and

this operation is the only opportunity to restore movable element 23 to its normal position. This complication is in many cases intentionally introduced.

In cases where the .perfect order of the hydraulic system is not so important, and if it is out dismounting it, spring means may be provided, for instance in the right hand side of valve body 22, acting on the movable element to restore it to its regular position. Instead of the spring means, the movable element 23 could The embodiment illustrated by Fig. 3 of the drawing corresponds to' the same principle applied to the case of a single acting servo-motor. In this embodiment, I have chosen, for the corresponding parts, the same reference characters as in Figs. 1 and 2. The pressure of the normal circuit is fed, through conduit 24, to distributing device 22, and it acts, through the connecting pipe 28 of the distributing device, in the chamber 35 of servo-motor 20, so as to push the piston 2i thereof toward the left (arrow 1). The outflow from the servo-motor then takes place through conduit 29, and conduit 25, which communicates with conduit 29 through body 22.

The fluid passes to a conduit 31, in which is fitted a three way cock 38. This cock is adapted to place conduit 25 in communication with a conduit 39 adapted to be fed with fluid under pressure, for instance from a pump.

This device will operate in the following manner:

In the case of a breakdown occurring in the normal fluid circuit 24-25, the pilot opens the cock 33 of the emergency conduit 32 which is connected to a source of auxiliary pressure. The fluid under pressure thus fed from said source pushes slide valve 23 toward the left, so as to cut oil both of the normal conduits and 25 of the servo-motor. Simultaneously, conduit 28 is connected to conduit 32, and conduit 29 is placed in communication with conduit 3|. Thus. the piston 2i of the servo-motor is operated, in the direction of arrow i the outflow of the fluid from chamber 36 taking place through conduit 29, the body 22 of the distributing device and conduit 3i, which opens directly into the atmosphere. In order to be able to bring back slide valve 23 into the normal working position thereof (which is the position illustrated in dotted I lines in Fig. 3) I place, through cock 38, or any other equivalent part, conduit 25:: in communication with conduit 39 which, as above explained, is fed with a fluid under pressure by a pump or the like. This fluid pushes back slide valve 23 toward the right.

In a general manner, while I have, in the above description, disclosed what I deem to be practical and eflicient embodiments of the present invention, it should be well understood that I do not wish to be limited thereto as there might be changes made in the arrangement, disposition and form of the parts without departing from the principle of the present invention as comprehended within the scope of the appended claims.

What I claim is:

1. A system of the type described, which comprises a hydraulic servomotor, said servomotor being connected by two pipes to valve means controlling the supply and discharge of fluid, said valve means comprising a valve body having two distributing ports connected to said pipes, two inlet and outlet ports, at least one of said ports being adapted to communicate with a source of fluid under pressure, a separate inlet port adjacent one end of said valve body, a conduit connecting said separate inlet port to another source of fluid under pressure, and a separate outlet port. a movable valve element inside said valve body, including pressure responsive means, said element being adapted to afford, in one position. communication between said inlet and outlet ports and said distributing ports, while obstructing said separate outlet port. and to aiford, in

its second position, communication between said separate inlet port and one of said distributing ports and between said separate outlet port and the other distributing port while obstructing the communication between said distributing ports and said first mentioned inlet and outlet ports, and further valve means to admit fluid under pressure from said conduit to said pressure responsive means to shift'said movable valve element from the flrstto the second position.

2. A system of the type described, which comprises a, hydraulic servomotor, said servomotor being connected by two pipes to valve means controlling the supply and discharge of fluid, said valve means comprising a valve body having two distributing ports connected to said pipes, an inlet port adapted to communicate with a source of fluid under pressure, an outlet port, a separate inlet port adjacent one end ofsaid valve body, a conduit connecting said separate inlet port to another source of fluid under pressure, and a separate outlet port, a movable valve element in said valve body, including pressure responsive means, said element being adapted to afford, in one position, communication between said inlet and outlet ports and said distributing ports, while obstructing said separate outlet port, and to aflord, in its second position,

communication between said separate inlet port and one of said distributing ports and between said separate outlet port and the other distributing port while obstructing the communication between said distributing ports and said first mentioned inlet and outlet ports, and further valve means to admit fluid under pressure from said conduit to said pressure responsive means to shift said movable valve element'from the first to the second position.

3. A system of the type described, which comprises a hydraulic servomotor. said servomotor being connected by two pipes to valve means controlling the supply and discharge of fluid,

- said valve means comprising a valve body having two distributing ports connected to said pipes, two inlet and outlet ports adapted to communicate alternatively with a source of fluid under pressure, a separate inlet port adjacent one end of said valve body, a conduit connecting said separate inlet port to another source of fluid under pressure, and a separate outlet port, a movable valve element in said valve body, in-

cluding pressure responsive means, said element 4 the 'first to the second position.

4. A system according to claim 1 in which said valve body has a cylindrical bore, said movable valve element having three piston-like portions slidably engaging the wall of said cylindrical bore, anad two recessed portions to form two annular chambers inside said valve body.

JEAN MERCIER. 

